Tobacco raw material, method for manufacturing same, and tobacco product

ABSTRACT

The present invention provides a tobacco raw material having a good smoking flavor and a method for producing the same. Provided is a tobacco raw material having a ratio, which is expressed as “water-extracted material weight/hexane-extracted material weight,” between the weight of an extracted material obtained by extraction using n-hexane as a solvent and the weight of an extracted material obtained following the extraction by further extraction using water as a solvent, of 0 or more and 1.5 or less.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of PCT International Application No.PCT/JP2014/072244, filed on Aug. 26, 2014, which claims priority under35 U.S.C. 119(a) to Patent Application No. 2013-175626, filed in Japanon Aug. 27, 2013, all of which are hereby expressly incorporated byreference into the present application.

BACKGROUND OF THE INVENTION

The present invention relates to tobacco raw material and a method ofproduction thereof.

BACKGROUND ART

Known methods for adjusting the smoking flavor of tobacco include art inwhich specific components are extracted and removed from a leaf tobaccomaterial, and art that entails carrying out an extraction operation on aleaf tobacco material so as to obtain an extract and an extractionresidue, carrying out a given treatment, etc. on the extract, thenre-applying the treated extract to the extraction residue.

A known technique for extracting and removing specific components from aleaf tobacco material involves removing lipid components from tobaccousing a mixed solvent of an aliphatic hydrocarbon and a lower alcohol(Patent Document 1).

A known technique for carrying out an extraction operation on a leaftobacco material and re-applying the extract to the extraction residueinvolves the method of carrying out extraction on tobacco raw materialwith a surfactant-containing solution, removing the surfactant andpolypeptides within the extract, and then adding the resulting solutionto the tobacco raw material (Patent Document 2).

A method for reducing nitrosamines from tobacco raw material thatentails using a supercritical fluid to treat the tobacco raw materialand removing nitrosamines from the extract obtained by such treatment isalso known (Patent Document 3).

Yet another technique that is known involves condensing the smokingflavor components present in a leaf tobacco material on the surface ofthe leaf tobacco via the operations of immersing the leaf tobaccomaterial under applied pressure in carbon dioxide that has been renderedinto a supercritical liquid, and then lowering the pressure toatmospheric pressure (Patent Document 4).

Patent Document 1: Japanese Examined Patent Publication No. S58-4544

Patent Document 2: Japanese Translation of PCT Application No. H7-505521

Patent Document 3: Japanese Patent No. 3931084

Patent Document 4: Japanese Patent Application Laid-open No. H8-23952

SUMMARY OF THE INVENTION

Leaf tobacco materials contain many components of differing polarities.Such components are broadly divided into low-polarity, high-polarity andbipolar components. When carrying out the removal of these components byextraction, such as when carrying out extraction with a low-polaritysolvent, the low-polarity and bipolar component groups within the leaftobacco are removed.

By contrast, when carrying out extraction with a high-polarity solvent,the high-polarity and bipolar components within the leaf tobaccomaterial are removed.

Hence, with a single extraction using a low-polarity or high-polaritysolvent, in addition to the low-polarity or high-polarity components,the group of bipolar components is also removed. This sometimes has alarge influence on the smoking flavor of the tobacco raw material.

Also, in the case of art which, after carrying out extraction, adds theextract to tobacco raw material, the group of components obtained by asingle extraction includes numerous components. When the extract hasbeen treated (such as by contact with an antioxidant), in addition tothe components to be removed, the components which affect the smokingflavor are also thought to change. Hence, there seems to be apossibility of a large influence on the smoking flavor.

It is therefore an object of this invention to provide a tobacco rawmaterial having a good smoking flavor. Another object is to provide amethod of producing such a tobacco raw material.

The inventors have conducted extensive investigations, as a result ofwhich they have discovered that a tobacco raw material, having a ratio,which is expressed as “water-extracted material weight/hexane-extractedmaterial weight,” between the weight of an extracted material obtainedby extraction using n-hexane as a solvent and the weight of an extractedmaterial obtained following the extraction by further extraction usingwater as a solvent, of 0 or more and 1.5 or less, has an excellentsmoking flavor.

In addition, the inventors have also discovered that the above problemscan be resolved by a method of production that includes: a firstextraction step of extracting a leaf tobacco material using a solventhaving a dielectric constant of 1 or more and less than 25 to obtain anextract and an extraction residue; a second extraction step of,following the first extraction step, extracting the extraction residueobtained in the first extraction step with a solvent having a dielectricconstant of 25 or more to obtain an extraction residue; and the step ofre-applying the extract obtained in the first extraction step to theextraction residue obtained in the second extraction step so as to forma leaf tobacco raw material. These discoveries ultimately led to thepresent invention.

The invention is recited below.

-   [1] A tobacco raw material having a ratio, which is expressed as    “water-extracted material weight/hexane-extracted material weight,”    between the weight of an extracted material obtained by extraction    using n-hexane as a solvent and the weight of an extracted material    obtained following the extraction by further extraction using water    as a solvent, of 0 or more and 1.5 or less.-   [2] The tobacco raw material according to [1], wherein the sum of    the weight of an extracted material obtained by extraction using    n-hexane as the solvent and the weight of an extracted material    obtained following the extraction by further extraction using water    as the solvent is from 5 to 17 wt % of the weight of the tobacco raw    material before the extractions.-   [3] A method of producing a tobacco raw material, which method    includes: a first extraction step of extracting a leaf tobacco    material using a solvent having a dielectric constant of 1 or more    and less than 25 to obtain an extract and an extraction residue; a    second extraction step of, after the first extraction step,    extracting the extraction residue obtained in the first extraction    step using a solvent having a dielectric constant of 25 or more to    obtain an extraction residue; and the step of re-applying the    extract obtained in the first extraction step to the extraction    residue obtained in the second extraction step so as to form a leaf    tobacco raw material.-   [4] The production method according to [3], wherein the solvent used    in the first extraction step is a solvent having a dielectric    constant of from 1 to 20 and the solvent used in the second    extraction step is water.-   [5] The production method according to [3] or [4], wherein the    solvent used in the first extraction step is one or more selected    from among n-hexane, tetrahydrofuran and ethanol.-   [6] A tobacco raw material obtained by the production method    according to any one of [3] to [5].-   [7] A tobacco product which uses the tobacco raw material according    to [1], [2] or [6].

In this specification, “leaf tobacco material” refers to a material usedto produce “tobacco raw material”, and means leaf tobacco prior topassing through treatment such as extraction steps. Also, “tobacco rawmaterial” refers to the product obtained by applying treatment such asextraction steps to the “leaf tobacco material”.

The invention provides a tobacco raw material having a good smokingflavor, and also provides a method of producing the same.

Further features of the present invention will become apparent from thefollowing description of exemplary embodiments (with reference to theattached drawings).

BRIEF DESCRIPTION OF THE DIAGRAMS

FIG. 1 is a graph showing sensory evaluation results for Example 3 andComparative Example 2.

FIG. 2 is a graph showing sensory evaluation results for Example 4 andComparative Example 3.

FIG. 3 is a graph showing sensory evaluation results for Example 5 andComparative Example 4.

FIG. 4 is a graph showing sensory evaluation results for Example 6 andComparative Example 1.

FIG. 5 is a graph showing sensory evaluation results for ComparativeExamples 5 and 6.

FIG. 6 is a graph showing sensory evaluation results for ComparativeExample 7.

DESCRIPTION OF THE EMBODIMENTS

The invention is described in detail below by way of embodiments,examples and the like. However, the invention is not limited to thefollowing embodiments and examples, and may be practiced using anymodifications thereto insofar as they do not depart from the spirit andscope of the invention.

<Production Method of the Invention>

The inventive method of producing a tobacco raw material includes: afirst extraction step of extracting a leaf tobacco material using asolvent having a dielectric constant of 1 or more and less than 25 toobtain an extract and an extraction residue; a second extraction stepof, after the first extraction step, extracting the extraction residueobtained in the first extraction step using a solvent having adielectric constant of 25 or more; and the step of re-applying theextract obtained in the first extraction step to the extraction residueobtained in the second extraction step so as to form a leaf tobacco rawmaterial.

The inventive method of producing a tobacco raw material includes, as afirst extraction step, the step of extracting a leaf tobacco materialusing a solvent having a dielectric constant of 1 or more and less than25 so as to obtain an extract and an extraction residue.

The leaf tobacco material that may be used in this invention is notparticularly limited as to type. Illustrative examples include genusNicotiana varieties such as flue-cured and burley varieties of nicotianatabacum, and the brasilia variety of nicotiana rustica.

These leaf tobacco materials are cut to a suitable size (having aparticle diameter of about 0.425 to 1.18 mm) using suitable means suchas a grinding mill. Use may be made of such materials that have beendried by a known method.

When the leaf tobacco material obtained by the foregoing treatment isextracted using a solvent having a dielectric constant of 1 or more andless than 25, the desired smoking flavor components contained in theleaf tobacco material can be extracted.

The solvent used in the first extraction step is more preferably onehaving a dielectric constant of 1 or more and 20 or less.

Illustrative examples of solvents having a dielectric constant of 1 ormore and less than 25 include ethanol, isopropyl alcohol, ethyl acetate,linear or branched alkanes of 5 to 10 carbons, n-propyl alcohol,butanol, benzene, toluene, xylene, benzyl alcohol, acetone,tetrahydrofuran, diethyl ether, 1,4-dioxane, chloroform anddichloromethane.

Examples of the alkanes include pentane, n-hexane, cyclohexane, heptane,octane, nonane and decane.

Of the above, embodiments that do not use a low-molecular-weight organicester such as ethyl acetate can be exemplified.

Solvents that may be preferably used include ethanol, n-hexane, heptane,diethyl ether and tetrahydrofuran.

The solvent having a dielectric constant of 1 or more and less than 25may be of a single type used alone or a plurality of such solvents maybe used in admixture. In cases where a mixed solvent is used, thedielectric constant of the mixed solvent is adjusted to 1 or more andless than 25.

Extraction may be carried out at normal temperature and pressure, or maybe carried out with warming to, for example, about 40 to 80° C. andunder an applied pressure of from 1,000 to 2,000 psi. When indicatingthe pressure in the SI unit system, calculation is carried out at aconversion factor of 1 psi 6,894.757 Pa.

The extraction time is not particularly limited and may be, for example,from 5 minutes to 1 hours.

Extraction may be carried out once or may be carried out a plurality oftimes. Extraction may be carried out using the subsequently describedaccelerated solvent extraction system.

In the first extraction step, an operation for separating the extractand the extraction residue may be suitably provided. For example, themethod of applying the extracted material to filter paper or a sievehaving a suitable pore size, and thereby separating it into an extractand an extraction residue may be used.

The resulting extraction residue is dried by a suitable method. Thedrying method is exemplified by freeze-drying.

By additionally carrying out, on the extraction residue obtained via thefirst extraction step, an extraction operation using a solvent having adielectric constant of 25 or more, components within the leaf tobaccomaterial that were not extracted in the first extraction step can beextracted.

The solvent having a dielectric constant of 25 or more that is used inthe second extraction step is not particularly limited. Illustrativeexamples include water, methanol, and mixed solvents containing these.

The second extraction step, as with the first extraction step, may becarried out at normal temperature and pressure as the extractionconditions. Extraction may also be carried out with warming to about 40to 80° C. and under an applied pressure of 1,000 to 2000 psi.

The extraction time is not particularly limited, and may be set to from5 minutes to 1 hour.

Extraction may be carried out once or may be carried out a plurality oftimes. Also, extraction may be carried out using the subsequentlydescribed accelerated solvent extraction system.

In the first extraction step and the second extraction step, because thesolvent used in the second extraction step has a higher dielectricconstant than the solvent used in the first extraction step, componentswithin the leaf tobacco material that were not extracted in the firstextraction step can be extracted in the second extraction step. Theextract obtained in the second extraction step is not re-applied to theextraction residue.

In the second extraction step, unwanted components contained in the leaftobacco material can be removed from the extraction residue obtained inthe first extraction step.

Examples of unwanted components include high-polarity components, suchas low-molecular-weight organic acids and ammonia.

In the production method of the invention, the order of the firstextraction step and the second extraction is important. That is, it isimportant to use a relatively low-polarity solvent as the solvent in theinitial extraction step, and to use a relatively high-polarity solventhaving a higher dielectric constant than the solvent used in the firstextraction step as the solvent in the next extraction step. If thisorder is reversed, a tobacco raw material having a good smoking flavorcannot be obtained.

It is possible to carry out the first extraction step a plurality oftimes and then carry out the second extraction step a plurality oftimes, or to carry out the first extraction step and the secondextraction step in succession and then repeat this by again carrying outthe first extraction step and again carrying out the second extractionstep.

From the standpoint of simplifying the production steps, it is desirablefor the total number of steps represented by the first extraction andsecond extraction steps to be small.

The production method of the invention includes the step of, afterpassing through the second extraction step, re-applying the extractobtained in the first extraction step to the extraction residue obtainedby passing through the second extraction step so as to form a leaftobacco raw material.

In this step, by re-applying the extract obtained in the firstextraction step to the extraction residue obtained in the secondextraction step, components that were extracted in the first extractionstep and are desirable for the smoking flavor of the tobacco rawmaterial are returned to the tobacco raw material.

When re-applying the extract to the extraction residue, having theextract spread uniformly throughout the extraction residue is desirablefrom the standpoint of maintaining uniformity of quality as a tobaccoraw material.

The extract obtained in the first extraction step, the extract obtainedin the first extraction step may be re-applied directly as is, or may bere-applied after concentrating the solvent only. Alternatively, theextract may be subjected to salting-out treatment.

After the extract has been re-applied to the extraction residue, thesolvent is removed by a suitable method.

It is possible in this way to obtain the tobacco raw material of theinvention.

The mode of use of the tobacco raw material obtained by the productionmethod of the invention is exemplified by use at normal temperature anduse in a warmed state, and the smoking flavor when used in either ofthese ways is excellent.

Modes of use at normal temperature or under heated conditions areexemplified by use in which leaf tobacco obtained by the above treatmentis filled into, for example, a tube having a bore of 0.7 mm and used.

Modes of use in a warmed state are exemplified by use in which the leaftobacco is warmed to, for example, about 40 to 70° C.

<Tobacco Raw Material of the Invention>

The tobacco raw material of the invention has a ratio, which isexpressed as “water-extracted material weight/hexane-extracted materialweight” (or “W/H ratio”), between the weight of an extracted materialobtained by extraction using n-hexane as a solvent (also referred tobelow as “hexane-extracted material”) and the weight of an extractedmaterial obtained by extraction using water as a solvent (also referredto below as “water-extracted material”), of 0 or more and 1.5 or less.

This tobacco raw material, by having such a W/H ratio, is a tobacco rawmaterial with a good smoking flavor. At a W/H ratio greater than 1.5,i.e., at a content of water-extracted material that is too large, thetobacco raw material has a smoking flavor that is adulterated.

In another embodiment, the W/H ratio may have a value of 0.3 or more and0.6 or less.

The sum of the weight of the hexane-extracted material and thewater-extracted material in the tobacco raw material of the inventionmay be from 5 to 17 wt %, based on the weight of the tobacco rawmaterial prior to extraction. In another embodiment, this may be from 5to 14 wt %.

Production of tobacco raw material having such a W/H ratio may involvethe use of, for example, the above-described tobacco raw materialproduction method of the invention.

The following method may be used as the method of measuring, within thetobacco raw material, the amount of extracted material that can beobtained by extraction using n-hexane as the solvent and the amount ofextracted material that can be obtained by subsequent extraction usingwater as the solvent. Specifically, an accelerated solvent extractionsystem (ASE 200, from Dionex) is used and a sample-filled cell isprepared by placing 1.0 g/cell of tobacco raw material in apressure-resistant extraction cell made of metal and having a volume of22 mL. The cell is mounted in the accelerated solvent extraction system,and extraction is carried out under the conditions shown in the tablebelow.

TABLE 1 PREHAT STATIC FLUSH %/ PURGE PRESSURE Temperature Number Solvent(min) (min) CYCLES (sec) (psi) (° C.) of vials n-Hexane 0 10 150%/ 902000 70 1 3 cycles Ultrapure 0 10 150%/ 90 2000 100 3 water 3 cycles

In the above extraction, the extract is transferred to a specializedglass vial for the solvent extraction system, this extract beingcollected following extraction and used to measure the amount ofextraction (see below for the method). A single cycle in solventextraction consists of pressurized filling of the solvent, warming,standing at rest, purging (transfer of solvent to the vial) and, onceagain, pressurized filling of the solvent. In the case of n-hexane,three cycles are repeated and the total amount of liquid obtained fromone cell is collected in one vial. When water extraction is successivelycarried out, a total of nine cycles are repeated and the total amount ofliquid obtained from three cycles is collected in one vial. Hence, atotal of three vials can be obtained from one cell.

Measurement of the amount of n-hexane extraction is carried out asfollows.

A 1 vial/1 cell n-hexane extract is transferred to a pre-weighed 100 mLround-bottomed flask using n-hexane, ethyl acetate and ethanol, inaddition to which the vial is rinsed out, thereby collecting all of theextracted material in the flask. The round-bottomed flask is placed on arotary evaporator and the contents are vacuum-concentrated, then driedat normal temperature and reduced pressure for 3 hours with a vacuum oilpump. Concentration is carried out using a rotary evaporator equippedwith trapping balls, and the liquid temperature of the water tank is setto 25° C. or less. The weight of the flask after drying is measured, andthe difference is treated as the amount of n-hexane extracted material.

Measurement of the water-extracted material is carried out as follows.

A 3 vial/1 cell water extract is transferred, using ultrapure water, toa pre-weighed 500 mL interchangeable ground joint round-bottomed flaskfor freezing, in addition to which the vial is rinsed out so that all ofthe extracted material is recovered in the flask. The round-bottomedflask and its contents are frozen in the pre-freezing tank of afreeze-drying system and then connected to the freeze-drying system anddried. The weight of the flask after drying is measured, and thedifference is treated as the yield of water-extracted material.

EXAMPLES

The invention is described more fully by way of examples. However, theinvention, insofar as it does not depart from the spirit and scopethereof, is not limited to the following examples.

The invention is described more fully below by way of examples. However,the invention, insofar as it does not depart from the spirit and scopethereof, is not limited to the following examples.

Example 1

Leaf tobacco material (a domestically produced burley variety) wasground using a grinding mill.

The grinding mill used was an SK-M10 Sample Mill from Kyoritsu Riko K.K.The ground material was then immediately applied to a sieve, giving aground leaf tobacco material having a particle size of from 0.425 mm to1.18 mm. Next, 2 g of this ground leaf tobacco material was preciselyweighed and filled into a metal cell.

The voids that formed during filling were filled using stainless steelbeads. The cell used was a 22 mL extraction cell made by Dionex, and thebeads were 2.2 mm diameter beads from Central Scientific Commerce, Inc.Solvent was delivered to this cell, and an accelerated solventextraction system was used to carry out extraction on the ground leaftobacco material.

The extractor used was an ASE-200 accelerated solvent extraction systemfrom Dionex.

Solvents having a dielectric constant of 1 or more and less than 25,such as n-hexane (dielectric constant, 2) and ethanol (dielectricconstant, 24), were used for extraction.

In extraction with the above extractor using these solvents, thesequence consisting of first filling the cell with solvent, warming thecell, letting it stand at rest, then forcing out the solvent within thecell was repeated three times. The temperature during warming and thepressure conditions during standing at rest were as follows for therespective solvents.

-   n-Hexane: 70° C., 2,000 psi-   Ethanol: 80° C., 2,000 psi

The volume of extract obtained with these solvents was about 40 mL. Theextract was concentrated using an evaporator and, using the same solventas that used during extraction, was brought to a constant volume of 6.25mL in a suspended state. Extraction with water (dielectric constant, 80)as the solvent was then carried out. At the time of this extraction, thesame sequence was followed as for extraction with a solvent having adielectric constant of 1 or more and less than 25, but the temperatureduring warming and the pressure during standing at rest were set to 100°C. and 2,000 psi. Also, the three cycles carried out during extractionwith a solvent having a dielectric constant of 1 or more and less than25 was changed to nine cycles during extraction with water. The totalvolume of the extract was about 120 mL.

The extraction residue remaining in the cell following extraction wascompletely recovered and pre-frozen, then furnished to freeze-drying. AnFD-81 Freeze Dryer from EYELA was used for pre-freezing andfreeze-drying.

The entire amount of extract prepared as described above withlow-polarity solvent was uniformly re-applied to the dried extractionresidue, thereby giving a tobacco raw material according to theinvention.

The solvents used in the respective examples were as follows.

-   Example in which n-hexane was used: Example 1-   Example in which ethanol was used: Example 2

An example in which a tobacco raw material obtained using methanol(dielectric constant, 33) as the solvent in the first extraction stepwas treated as Comparative Example 1.

The ammonia contents were measured for the tobacco raw materials inExamples 1 and 2 and Comparative Example 1. Measurement of the ammoniacontent in the tobacco raw material was carried out by the followingprocedure.

<Ammonia Analysis>

Untreated raw material (180 mg) or treated raw material (having theweight obtained when 180 mg of untreated raw material has been treated)was immersed and extracted for 30 minutes in 5 mL of pure water. Theextract was then filtered with a 10 KDa ultrafiltration membrane. Thefiltrate was analyzed with a capillary electrophoresis chromatograph(Agilent Technologies). The absorbance was measured at a wavelength of280 nm and the ammonia was quantitatively determined as ammonium ionsusing an aqueous solution of ammonium chloride diluted to a suitableconcentration as the standard solution.

The quantitatively determined values converted to amounts based on theraw material weight are shown in Table 2. For the treated raw material,conversion was carried out using the raw material weight when untreated(in order to eliminate the influence arising from the weight lossdisparity due to treatment).

TABLE 2 Ctrl n-Hexane Ethanol Methanol Domestic burley tobacco 3066.90.0 483.8 1564.6 Brazilian flue-cured tobacco 365.3 0.0 — — Note: In thetable, “—” means not measured. Numerical values other than the controlsin the table are values obtained by converting quantitatively measuredvalues to amounts based on the weight of the raw material (ppm (W.B.)).

It is apparent from the results in Table 2 above that, in cases where asolvent having a dielectric constant of 1 or more and less than 25 wasused in the first extraction step and, after passing through the secondextraction step, the extract obtained in the first extraction step wasre-applied to the extraction residue, compared with cases in which asolvent having a dielectric constant of 25 or more was used in the firstextraction step, a large amount of ammonia was selectively removed.

<Sensory Evaluation>

With regard to tobacco raw material obtained by the production method ofthe invention, sensory evaluations of the sort described below werecarried out in Example 3, where the tobacco raw material was producedunder the same conditions as in Example 1; in Comparative Example 2,where it was obtained by carrying out only the operation of re-applyingthe extract obtained from the first extraction step (no secondextraction step); in Example 4 where it was obtained by, aside fromusing a Brazilian flue-cured variety as the leaf tobacco material,carrying out the same operations as in Example 1; in Comparative Example3, where it was obtained by carrying out only the operation ofre-applying the extract obtained from the first extraction step inExample 4 (no second extraction step); in Example 5, where it wasobtained from the same leaf tobacco material and operations as inExample 3; and in Comparative Example 4, where it was obtained from thesame leaf tobacco material and operations as in Comparative Example 2.The following operations were carried out during sensory evaluation.

Examples 3 and 4, and Comparative Examples 2 and 3

Untreated material that had been ground and sieved (particle size, from0.425 mm to 1.18 mm) and the respective tobacco raw materials (Examples3 and 4, and Comparative Examples 2 and 3) were filled into quartz tubes(9 mm (o.d.)×7 mm (i.d.)×55 mm (L)).

The fill weight was set to 180 mg for untreated raw material and incases where no extracted material was removed. In the case of a treatedraw material that included an extracted material removing step, takinginto account the amount of weight loss due to not re-applying thewater-extracted portion, the fill weight was set to 109 mg (the weightof the raw material obtained when 180 mg of raw material was treated).The sample was kept from scattering upon inhalation during evaluation bystopping both ends of the quartz tube with stainless steel mesh. Thesequartz tubes were heated to 60° C., inhalation was carried out from oneend of the tube, and the results compared with untreated raw materialwere examined.

<Sensory Evaluation Method>

The sensory evaluation (change in smoking satisfaction) criteria areshown below. The degree of change relative to untreated raw material wasrated using the 7-step scale expressed in terms of the language shownbelow. The number of subjects for each evaluation was set at ten people.The least significant difference (LSD) was used to determine thesignificance of differences in the sensory evaluation results due to thetreatment method. The results are shown in FIGS. 1 and 2.

(1) very strong: +3

(2) strong: +2

(3) somewhat strong: +1

(4) no change: +0

(5) somewhat weak: −1

(6) weak: −2

(7) very weak: −3

From the results in FIGS. 1 and 2, in tests by the least significantdifference method, there was a 95% significant difference between theexamples of the invention and the comparative examples, and so effectsdue to the production method of the invention were observed.

From this, regardless of differences in the variety of the leaf tobaccomaterial, such as domestic burley tobacco and Brazilian flue-curedtobacco, the tobacco raw material obtained by the production method ofthe invention was found to achieve an excellent smoking flavor.

Example 5 and Comparative Example 4

Untreated material that had been ground and sieved (particle size, from0.425 mm to 1.18 mm) and the respective tobacco raw materials (Example 5and Comparative Example 4) were filled into plastic tubes (9 mm (o.d.)×7mm (i.d.)×110 mm (L)).

The fill weight was set to 360 mg for untreated raw material and incases where no extracted material was removed. In the case of treatedraw material that included an extracted material removing step, takinginto account the amount of weight loss due to not re-applying thewater-extracted portion, the fill weight was set to 218 mg (the weightof the raw material obtained when 360 mg of raw material was treated).The sample was kept from scattering upon inhalation during evaluation bystopping both ends of the plastic tube with nonwoven fabric mesh. Usingthese plastic tubes, inhalation was carried out from one end of the tubeat room temperature, and the results in compared with untreated rawmaterial were examined. The results are shown in FIG. 3.

Evaluations on Example 5 and Comparative Example 4 were carried out inthe same way as for Examples 3 and 4 and Comparative Examples 2 and 3.As a result, in tests by the least significant difference method, therewas a 95% significant difference between Example 5 and ComparativeExample 4. Hence, effects due to the production method of the inventionwere observed.

Example 6

Aside from using tetrahydrofuran (dielectric constant: 8) as the solventfor extraction in the first extraction step, a tobacco raw material wasproduced by the same procedure as in Example 1.

The tobacco raw material of Example 6 (104.94 mg) and the tobacco rawmaterial produced in Comparative Example 1 (using methanol as thesolvent for extraction in the first extraction step; 134.55 mg) weresubjected to sensory evaluations (change in smoking satisfaction) by thesame method as in Examples 3 and 4 and Comparative Examples 2 and 3. Theresults are shown in FIG. 4.

Comparative Examples 5 and 6

Leaf tobacco material of a domestic burley variety was subjected togrinding treatment in the same way as in Example 1, and the firstextraction step was not carried out; only the second extraction step wascarried out (only extraction with water was carried out). The extractobtained by this second extraction step was re-applied to the extractionresidue, thereby producing a tobacco raw material for ComparativeExample 5.

Also, leaf tobacco material of a domestic burley variety was subjectedto grinding treatment in the same way as in Example 1 and the secondextraction step (extraction with water) was initially carried out,following which the first extraction step (extraction with n-hexane) wascarried out. Next, only the extract obtained by carrying out extractionwith water was re-applied to the extraction residue, thereby producing atobacco raw material for Comparative Example 6.

Sensory evaluations (change in smoking satisfaction) on the tobacco rawmaterials obtained in Comparative Examples 5 and 6 were carried out bythe same method as described above. The weight of the tobacco rawmaterial from Comparative Example 5 used in the sensory evaluation was180 mg, and the weight of the tobacco raw material from ComparativeExample 6 used in sensory evaluation was 172.9 mg. The results are shownin FIG. 5.

Comparative Example 7

Leaf tobacco material of a domestic burley variety was subjected togrinding treatment in the same way as in Example 1, the secondextraction step was carried out first (i.e., extraction with water wascarried out first), following which the first extraction step wascarried out (i.e., extraction with n-hexane was subsequently carriedout), and the extract thus obtained (n-hexane extract only) wasre-applied to the extraction residue, thereby producing a tobacco rawmaterial for Comparative Example 7.

Sensory evaluation (change in smoking satisfaction) was carried out forComparative Example 7 by the same method as described above for thetobacco raw materials obtained in Examples 3 and 4 and ComparativeExamples 2 and 3. The weight of the tobacco raw material fromComparative Example 7 used in the sensory evaluation was 83.86 g. Theresults are shown in FIG. 6.

<W/H Ratios of Tobacco Raw Materials>

The W/H ratios of the respective tobacco raw materials obtained inExample 1 (in which n-hexane was used in the first extraction step),Example 2 (in which ethanol was used in the first extraction step),Example 6 (in which tetrahydrofuran was used in the first extractionstep), and Comparative Example 1 (in which methanol was used in thefirst extraction step) were measured. As a reference example, the W/Hratio for untreated tobacco raw material (burley variety) was alsomeasured. The measurement method is as described above.

Filling of the samples used in extraction was carried out as follows.

Additive-free filter paper was set in a pressure-resistant metalextraction cell, and the cell was filled with 10 g of prewashed andweighed stainless steel balls. Next, the tobacco raw materials obtainedin Examples 1, 2 and 6, Comparative Example 1 and the reference examplewere weighed out, with an even balance, in respective amounts of 1.0g/cell onto powder paper and, using a suitable aid such as a powderfunnel, the weighed samples were placed in the already prepared 22 mLcells in which the filter paper and stainless steel balls had been set;sample remaining on the powder paper was wiped several times with thestainless steel balls and added to the cell. In addition, voids wereeliminated by packing the cell with stainless steel balls until it wasfilled to the top. Once the cell was completely filled, the top side wasclosed and the cell was tapped on a desk to bury any gaps and even outthe contents, after which the empty space was filled with stainlesssteel balls.

Next, under the conditions shown in Table 1, extraction with n-hexaneand water (MilliQ water) was carried out for 3 cycles and 9 cycles,respectively, and the weight of extracted material obtained byextraction with each of these solvents was determined. Measurement wascarried out twice for each of the tobacco raw materials, and the weightof the extracted material in each case was indicated as an average ofthe resulting measurements.

The W/H ratio and the ratio of the extracted material weight relative tothe tobacco raw material before the extraction treatment were determinedfrom the resulting extracted material weights. The results are shown inTable 3.

TABLE 3 Comparative Reference Example 1 Example 2 Example 6 Example 1Example n-Hexane extracted material 7.23 10.38 8.60 7.80 6.75 weightratio (%) Water-extracted material weight 2.55 5.43 2.70 16.45 39.55ratio (%) W/H ratio 0.4 0.5 0.3 2.1 5.9 Extracted material 9.8 15.8 11.324.2 46.3 weight/Tobacco raw material weight (%)

The apparatuses, solvents and products used were as follows.

<Apparatuses Used>

Accelerated solvent extraction system (ASE 200, from Dionex)

Even balance (PM 2500, from Mettler)

Freeze dryer with pre-freezer (FD-81, from Tokyo Rikakikai Co., Ltd.)

Vacuum oil pump (ULVAC GCD-051X, from ULVAC KIKO Inc.)

<Solvents Used>

n-Hexane (high-performance liquid chromatography (HPLC) grade, from WakoPure Chemical Industries, Ltd.)

Water (MilliQ water from Nihon Millipore K.K., obtained with MQ Gradientwater purification system)

Ethyl acetate (high-performance liquid chromatography (HPLC) grade, fromWako Pure Chemical Industries, Ltd.)

Ethanol (high-performance liquid chromatography (HPLC) grade, from WakoPure Chemical Industries, Ltd.) Note: The ethyl acetate and ethanol wereused when transferring n-hexane extracts to round-bottomed flasks.

<Products Used>

Powder paper: 10 cm square sheets

Interchangeable ground joint round-bottom flasks: 100 mL (SibataScientific Technology, Ltd.)

Interchangeable ground joint round-bottom flasks for freeze-drying: 500mL (EYELA K.K.)

Pressure-resistant metal extraction cells, 22 mL (Dionex)

Additive-free filter paper for extraction cells (Dionex)

Stainless steel balls, particle size, 2.3 mm (Central ScientificCommerce, Inc.)

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

1. A tobacco raw material having a ratio, which is expressed as“water-extracted material weight/hexane-extracted material weight,”between the weight of an extracted material obtained by extraction usingn-hexane as a solvent and the weight of an extracted material obtainedfollowing the extraction by further extraction using water as a solvent,of 0 or more and 1.5 or less.
 2. The tobacco raw material according toclaim 1, wherein the sum of the weight of an extracted material obtainedby extraction using n-hexane as the solvent and the weight of anextracted material obtained following the extraction by furtherextraction using water as the solvent is from 5 to 17 wt % of the weightof the tobacco raw material before the extractions.
 3. A method ofproducing a tobacco raw material, comprising: a first extraction step ofextracting a leaf tobacco material using a solvent having a dielectricconstant of 1 or more and less than 25 to obtain an extract and anextraction residue; a second extraction step of, after the firstextraction step, extracting the extraction residue obtained in the firstextraction step using a solvent having a dielectric constant of 25 ormore to obtain an extraction residue; and the step of re-applying theextract obtained in the first extraction step to the extraction residueobtained in the second extraction step so as to form a leaf tobacco rawmaterial.
 4. The production method according to claim 3, wherein thesolvent used in the first extraction step is a solvent having adielectric constant of from 1 to 20 and the solvent used in the secondextraction step is water.
 5. The production method according to claim 3,wherein the solvent used in the first extraction step is one or moreselected from among n-hexane, tetrahydrofuran and ethanol.
 6. A tobaccoraw material obtained by the production method according to claim
 3. 7.A tobacco product which uses the tobacco raw material according to claim1.